This grant application seeks continued support for the Pediatric Oncology Group (POG) activities of The University of Texas Southwestern Medical Center (UT Southwestern) Consortium, which consists of UT Southwestern (Dallas), Cook-Ft. Worth Children's Medical Center (Ft. Worth), and Scott & White Clinic (Temple). Since joining POG in 1981, this partnership of children's cancer treatment and research centers in North Texas has grown to become POG's largest contributing member with regard to patients enrolled on therapeutic studies (over 100 annually). During the current grant cycle, consortium investigators have held administrative and scientific leadership positions on major Group committees, including Executive Committee, Principal Investigator's Committee, New ALL Committee, T-cell Committee, and Lymphoid Relapse Committee. UT Southwestern Consortium investigators have also served or are serving as study coordinators on multiple POG treatment protocols studying ALL (newly diagnosed patients with B-lineage and T-cell disease as well as following relapse), non-Hodgkin's lymphoma, bone marrow transplantation and new agents being explored in Phase I-II trials. UT Southwestern Consortium investigators have also had prominent roles in the arenas of data management, protocol development, molecular and pharmacologic monitoring in authorized POG reference laboratories, and supportive care. Results of pilot projects conducted at UT Southwestern have been instrumental in the construct of group-wide treatment strategies, especially involving use of methotrexate for B-lineage ALL. To support the UT Southwestern Consortium's continued commitment to POG research during the next 5 years, this new grant proposal describes personnel and facilities in the 3 consortium centers. Specifically, during 1996-2000 the Consortium aims to advance POG research by: (l) enrolling as many patients as possible on POG treatment, biological classification, and epidemiology protocols; (2) collecting, recording, and submitting research data in an accurate and timely fashion; (3) providing administrative and scientific expertise to the Group through continued active participation on major committees, including service as disease committee chairs and protocol coordinators; and (4) continuing to conduct innovative in-house pilot studies for subsequent use by the Group.